Daniel Charraut

D.C. scanning thermal microscopy : Characterisation and interpretation of the measurement

Abstract The used Scanning Thermal Microscopy (SThM) probe is a thin Pt resistance wire acting as a heat source and as a detector simultaneously. Its energetic balance is investigated by the study of the temperature profile along the probe. A theoretical approach of the measurement, based on this investigation, is then proposed. Simulations with this modelling are shown to predict how the heat, electrically produced in the probe, is dissipated in the probe-sample system. In particular, it is shown that the steady-state of conduction losses to the thermal element support varies versus the thermal conductivity of the sample and can lead to bad interpretations of the measurement.

Simplifications of the bilinear transfer for microscopic binary objects

Microscopy of binary objects in partially coherent light is analyzed in terms of bilinear transfer. A transfer model using two apparent transfer functions is proposed. Its domain of validity is studied by numerical simulation.

Optical Modeling Of Line Object In Microelectronics Using Radiometric Approach

A simple model describing the field reflected on a trapezoidal shape highly reflecting object is proposed. This model is based on the assumption of non interference between the bottom and the top of the line under test. Some results of simulation are presented and discussed.

Distribution of light density inside metal-coated micrometer-size optical tapers

We tackle the complex problem of taper heating inside an optical fiber tip used in scanning near-field optical microscopes. The technique is based on the usual ray tracing. Its interest is in the modeling, taking into account not only the power input distribution but any shape of tapers. The thermal-optical behavior of a shell-shaped taper is compared with that of a pure conical taper. Sharp power concentration peaks inside nonlinear taper profiles have been demonstrated, in contrast with the smooth power distribution inside cone shapes. The results present heat zones that are in agreement with our thermal model.

Analysis of optical near-field images by Karhunen–Loève transformation

With regard to classical image transformations, the Karhunen-Loève transform is based on the statistical analysis of signal or image data. We propose using it to analyze and recognize the content of images generated in near-field microscopy. It is shown that such a transform is an efficient tool for separating actual information from noise without reducing the spatial-frequency band.

Karhunen-Loeve transform in optical microscopy: application to linewidth measurement

The linewidth measurement on wafers depends on the smallnlocal irregularities in the region being tested. Such defects must be firstnof all detected and then canceled in order to give an estimation of thenaverage linewidth. Image processing based on the Karhunen-Loeve transformnof multiple acquisitions in different experimental conditions is proposed.nUsing statistical information compression, irregularities are easilyndetected and efficient noise filtering is performed.

Mesure de largeurs de trait en éclairage partiellement cohérent par modélisation du transfert et utilisation de techniques de moindres carrés

RésuméUne méthode de modélisation du transfert en microscopie partiellement cohérente est présentée. En comparant alors, par une technique d’estimation d’erreur basée sur les moindres carrés, les données expérimentales et simulées, il est possible de déterminer avec précision la largeur de traits sur circuits intégrés.AbstractA method of transfer modelling in partially coherent microscopy is presented. By determining the minimal error between simulated and experimental data by means of a lms technique, it is then possible to retrieve, with accuracy, the linewidth on wafers.

A new THz passive radial polarizer

A new THz radial polarizer suitable to convert the usual linearly polarized signal from a millimeter or sub-millimeter source is described. It is based on mode-filtering within a cylindrical waveguide combined with two tapers and a discontinuous phase element. An experimental demonstration is given at ap 100 GHz and transposition to higher THz frequencies by scaling is straightforward.

Optical near-field image processing by the Karhunen-Loeve transform

In near-field microscopy, the Karhunen-Loeve transform could be an efficient tool for separating actual information from noise without reducing the spatial frequency band. Both experimental data and simulations are analyzed using such a signal processing.